Influence of capping layer on the properties of MOVPE-grown InAs/GaAs quantum dots

During the capping process of InAs/GaAs quantum dots (QDs), the redistribution of In atoms decreases the height of QDs and changes their shape. These changes can be influenced not only by the composition of the covering strain reducing layer but also by the growth parameters of layers covering QDs. We have studied the effect of GaAs capping layer growth rate on the QD properties. It was found that a higher GaAs capping layer growth rate enhances the surfactant behavior of In atoms and diminishes the alloying effect in QD surrounding material. Higher capping layer growth rate can also decrease the dissolution of In atoms from QDs. The capping layer growth rate has stronger effect on the ground state photoluminescence (PL) maximum energy, when InGaAs strain reducing layer is not present in the structure.